I have seen in our analytics a marked decrease in data pulling through for visits to our secure site pages from iPhone devices as of mid February 2019. Wondering if anyone has seen similar results and if know reasons as to why - other than standard difficulties in tracking Apple data.
It's possible that this is related to Apple's Intelligent Tracking Prevention (ITP) initiative. ITP is supposed can impact how visitors using Apple products are tracked on your site, including cookie persistence, cross-domain tracking, and third-party cookie blocking. The impact varies according to how you've implemented Adobe Analytics.
The timeframe mentioned seems to coincide with Apple's ITP 2.1 announcement February 21st, though I'm not sure that this went into effect immediately. I would only expect this to be an issue if these were browser visits on the device as well.